This disclosure relates generally to the field of electronics and, more specifically, to systems and methods for suppressing transient voltages across a relay coil.
Power conditioning units (PCU's) use airborne aircraft +28 Vdc bus to power relay coils. These coils are normally rated for +29 Vdc maximum, with a few rated for +32 Vdc maximum. The +28 Vdc power specification is 22 to 29 Vdc, with an additional 1.5 V of ripple. In addition, a 50 V transient voltage may also be present.
To solve transients and over voltage conditions on the +28 Vdc bus, past attempts have included connecting a zener diode or a transient suppressor across the bus, or by simply doing nothing. Zener diodes and transient suppressors suffer from the limitation that they will most likely burn up after only one over voltage condition. What is needed is an apparatus and method that handles such transient voltage conditions without destroying components in a PCU.